关键词: 棉花, CO₂浓度, 氮肥, 生物量, 氮吸收, 土壤脲酶活性

Abstract: Patched distribution of vegetation is the result of the longterm adaptation and selfadjusting of plants in waterlimited environment, and the vegetation succession process can be used as the indicator of the abrupt change of ecosystems affected by climate change and human activities. This paper reviewed the origin of patched vegetation, related ecohydrological processes, and their implications on the vegetation restoration in arid areas, and discussed the existing problems in the vegetation restoration in arid areas. It was considered that the origin of patched vegetation could be affected by the climate change, human activities, reproduction characteristics of plant species and their adaptation to the environmental stress, but the key for the formation and stabilization of patched vegetation in arid areas was the water redistribution in the patches with and without vegetation in different space scales. Bare land is the “source” of the runoff in the whole ecosystem, while patched vegetation is a highefficient water harvesting system, being the “sink” of the runoff in the whole ecosystem. Therefore, to protect vegetation patch while keeping a certain area of bare land is vital to the water redistribution and vegetation restoration in arid areas. Patched vegetation is also a very fragile ecosystem, both the extreme climate change and the excessive human activities can contribute to the loss of the function of patched vegetation ecosystem, leading to an irreversible consequence, and thus, a strict protection is needed for patched vegetation.

Key words: cotton, CO₂ concentration, nitrogen fertilizer, biomass, nitrogen absorption, soil urease activity.